The effect of cerebral ischemia and postischemia on the synaptosomal uptake of some neutral amino acids was determined in Mongolian gerbils at various periods of time. A transiently increased uptake of 3H isoleucine, 14C cycloleucine and 3H phenylalanine in the synaptosomes was found after 3 minutes of bilateral common carotid occlusion which returned to normal at 30 minutes of reestablished cerebral blood circulation.